The fixture is designed based on the principle of a reflective three-shade system, which directs the majority of the light downwards. The shades are made of handblown opal three-layer glass, which is glossy on top and sandblasted matte on the underside, giving a soft and uniform light distribution. The PH 3½-3 Glass Pendant is one of many advanced projects undertaken by Poul Henningsen in the development of his world-famous three-shade system from 1926. Poul Henningsen devoted most of his life to taming electric light. He based his three-shade design on a logarithmic spiral to make optimum use of the light source. He was constantly doing calculations and tests. The form of the shades was determined by the way they were required to shape and reflect the light, and the lamp was designed to be glare-free. The white opal glass shades soften the overall look of the lamp and illuminate its surroundings with a perfect, harmonious and glare-free light that only the classic three-shade system is capable of emitting. The shades are mouth-blown three-layer opal glass, which is glossy on top and sandblasted matt underneath to provide soft and uniform light distribution.